New York City firefighter Robert Ryan, 48, was one of the most experienced triathletes the FDNY had ever seen when he joined the department in 1983.
By his own count, he has run 45 triathlons to 50 triathlons -- including the fabled "Iron Man" competition in Lake Placid, N.Y., in 2002.
"Prior to 9/11, my lung capacity was 130 percent, meaning I had 30 percent better lung capacity than the average citizen," he said to ABC News. "By January 2005, my capacity was down to 100 percent, and in April , it was measured at 80 percent, and it's just getting worse."
Ryan now has trouble climbing a flight of stairs, but it really hurts when he tries to play with his 7-year-old son.
"I want to be active with him, but after 10 [minutes] or 15 minutes of biking or swimming, I'm shot," Ryan said. "And he knows that. He'll ask me, 'Are you OK? Are you OK?'"
In August, Ryan packed up and moved with his son and girlfriend Patricia to Glendale, Ariz., because the air quality made it easier for him to breathe.
He suffers from asthma, acid reflux, respiratory airway disease syndrome, and "every time I get a cold or something small, it blows up into something big. I've had an infection for three weeks now," he said.
Ryan worked at ground zero "on and off until February 2002."
Like many firefighters, he said that in all the time he was working there, he was never given a mask, but he also said he never asked for one.
"As far as our own safety and the thought that we had about going in there -- nobody gave it a thought. Every fireman, cop that went down there, nobody thought about [their] own safety," he said. "That's not what we do. We run into burning buildings. Cops chase criminals. That type of thing. It's what we do."
"We had no protection at all," he said. "We had no tools and so whatever you grabbed, you could bring -- guys were bringing shovels and things from home."
Ryan believes that the department and the city were caught off guard by how many firefighters were getting sick, and says it was last January that the department changed its procedures to restrict more firefighters from claiming 9/11 injuries and ailments.
In January 2005, the department stopped using the methocholine test, an asthma test, and changed to a pulmonary function test, "which is OK if you have a blockage in your lungs."
"But if your lungs aren't irritated at the time you take the [pulmonary function] test, it's not going to show up," he said.
"They knew what they were doing,'' he said, of the policy shift, which was confirmed to ABC News by United Firefighters Association president Steve Cassidy.
"There were guys coming in a year after 9/11 getting full benefits with lesser symptoms than some of us have now," Ryan said. "I think the department was just overwhelmed by the number of people getting sick four and five years out, and they're making it harder for us to prove because of economics."
He said his brother, another 9/11 firefighter who worked for weeks at ground zero, had an operation to remove a cancerous tumor in his pancreas.
"We have a saying at the firehouse. … 'We went from heroes to zeroes,'" Ryan said.
"Every guy that was down there gave 150 percent, and now they're getting slapped in the face," Ryan said, echoing a sentiment ABC News heard many times over several weeks of interviews with New York firefighters.
"I'm not talking about millions of dollars for each one," he said. "I'm talking about being able to take care of your family when you have to retire at 41 [years old] or 45 years old."
Ryan went to a triathlon training session in 2004, but after watching him struggle through a few laps in the pool, the track coach told him to forget it.
"My triathlon days are over, so I'm going to focus on maybe becoming a coach myself," he said.